DE102005017765B4 - Method for adjusting a device for imaging printing plates - Google Patents

Abstract

Method for setting a device for imaging printing plates (2) with at least two imaging elements (4) spaced apart from one another in an X direction and designed to be able to image parts of a printed image seamlessly and without offset to one another, for which purpose the imaging elements ( 4) Target positions are assigned and actual positions of the imaging organs (4) are checked at least relative to each other at least in a direction orthogonal to the X direction Y direction and unwanted effects are thereby prevented or compensated for misalignments, wherein for checking the actual positions in the Y-direction of each imaging member (4), the printing plate (2) with respective right and left in the Y-direction column (12a, 12b), each with at least three in the Y direction of spaced second patterns (22) so imaged in that in each case the right-hand column (12a) of an image part (6) of an imaging member (4) is moved to the left Column (12b) of an adjacent image part (6) adjacent to or overlapping with this, said second pattern (22) at least three aligned in the X direction, parallel, in the Y direction ...

Description

The The invention relates to a method for adjusting a device for imaging printing plates, in particular an outer drum printing platesetter, with at least two imaging members, preferably exposure heads, the are provided, image parts of a printed image seamless and without offset to be able to image each other for which the positioning organs are assigned nominal positions and Actual positions of the Bebilderungsorgane be checked at least relative to each other.

Becomes a printing plate of two or more imaging organs imaged, this results in the problem that the individual image parts of the resulting Print image seamlessly and without offset to connect to each other. Otherwise the connection points of the image parts are recognizable and diminish the qualitative impression of the printed image considerably.

The Bebilderungsorgane can in particular exposure heads be. these can be constructed of a plurality of laser diodes, a diode array or form a matrix. Instead of laser diodes, an exposure head z. B. also be constructed of optical waveguides, which in turn with Laser sources are connected.

The Information of the image to be imaged are initially in a file. This image file can in turn be divided into image areas, or be assigned to the individual Bebilderungsorganen. Each image area of the image file then gives one of a Bebilderungsorgan imaged part of the image. The individual parts of the picture close to connection points of the printed image to each other.

During the Exposure is the drum of the external drum imagesetter together turned on the clamped pressure plate. Through this rotation In the drum the imaging organs depict the printing plate in a so-called Fastscan direction or, if one is an orthogonal Coordinate system, in a Y direction.

The Bebilderungsorgane can orthogonal to this Y-direction in the so-called slowscan or X direction on a lead be moved, and then according to the movements in X and Y-direction, the individual parts of the image from the corresponding image Image areas of the image file.

to Movement of the imaging organs in the X direction can be the imaging organs be coupled or move independently of each other. A coupling can z. B. be achieved by the fact that the Bebilderungsorgane all through a spindle, which makes a rotational movement in a longitudinal Moves movement of the Bebilderungsorgane, moving in the X direction or by being all at a fixed distance from each other on a common carrier are held. The coupling of the imaging organs has the advantage that once made settings of the Bebilderungsorgane each other remain.

The Fixing the imaging organs, their orientation relative to Drum and tolerances in their own internal structure, as well as tolerances at the positioning of the imaging organs on the guide, or lead the spindle to misplacements of Bebilderungsorgane relative to each other.

These Lead missteps that different imaging organs are no longer, as in their own Target positions provided, lying on a common line Illustrate points. The of two neighboring imaging organs Imaged image parts then have an offset in the Y direction.

deviations the actual positions of the imaging organs of their desired positions to lead in particular also to the fact that different image parts overlap in the X direction can or a gap between them can arise and thus ensures no seamless connection is. It then enters a well recognizable offset of two adjacent Image parts in the X direction on.

In the patent US 5453777 A A method is presented for reducing the X and Y offsets of several exposure elements. As exposure elements laser organs are presented. These laser organs are all in a write head. Due to eccentricities of the laser organs, relative misalignments occur relative to each other under the individual laser organs. It is proposed that the Y offset be compensated by a time offset of the drive signals of the laser organs. The offsets in X-directions are said to be after the US 5453777 A will be corrected by a laser, the z. B. would illuminate the area of a previous laser with, only corresponding revolutions of the drum begins later with the exposure of its image part. He would then fully expose his attributed image part. How the offenses are to be recognized is not mentioned.

In the patent US 6,106,095 A A method for imaging letters by means of inkjet is described. To detect deviations of multiple inkjet heads from each other, test patterns of the adjacent heads are printed on an envelope. The test patterns are ver vertical and horizontal lines whose offset should be determined to each other to detect the deviations of the print heads. Due to the bar nature of the test patterns, the detection of the offsets is difficult.

The The object of the present invention is to provide a method with the quality of a resulting print image can be increased by a possible offset print image is generated, in particular a method is to be specified, the actual positions of the Bebilderungsorgane to check. in this connection it is in particular the task of deviations of the imaging organs to recognize quickly and safely.

This object is achieved by a method for adjusting a device for imaging of printing plates, in particular an outer drum Druckplattenbelichters, with at least two Bebilderungsorganen, preferably exposure heads, which are intended to image parts of a printed image seamlessly and without offset to each other, including the Bebilderungsorganen Soll -Positions are assigned and actual positions of the imaging organs are checked at least relative to one another, which is characterized in that the actual positions of the imaging organs (4) are checked in an X and / or a substantially orthogonal Y-directions, where to verify the actual positions:
In the Y direction of each imaging member, the printing plate, each having at least three, preferably a plurality of longitudinally spaced from each other, spaced second patterns so that each of the right column of an image part of a Bebilderungsorgans to the left column of a at least adjacent to adjacent image part.

in this connection In particular, it may also be provided that the respective overlap adjacent columns as well. Due to deviations of the second pattern from adjacent columns in the Y direction can then be advantageously to deviations of Actual positions of the Bebilderungsorgane of target positions in the Y direction is closed become. The use of at least three second patterns per column elevated while the quality of knowing. It can also be the clarity with which a misposition can be detected in the Y direction, thereby increased according to the invention be that alignment of the second patterns of a column straight so chosen is that just in a misposition a second pattern of first column with a second pattern of the second column one neighboring organ of illustration well recognizable in an escape in X-direction lies, this can be carried out in particular that practically a second pattern of the one imaging organ seamless in a second pattern of an adjacent Bebilderungsorgans passes. The second patterns can for example, from a first partial pattern and a complementary to this second Subpatterns exist.

In another method step, which may also be provided in addition, it is further provided that for checking the actual positions:
In the X direction of each imaging member, a printing plate having at least a first pattern overlapping at least a first pattern of at least one adjacent imaging member is imaged.

at Such a test pattern is advantageously always first a defined overlap, d. H. a defined offset of the image parts provided. X-offsets can then by possible deviations of the actual overlap from the defined overlap be advantageously identified, thereby indicating deviations the actual positions of the imaging organs of their desired positions can be closed.

It is according to the invention advantageously also provided that on the above-described Wise men realized they were prevented or compensated for. This can improve the quality the print image are improved because at least less offset occur in the X and Y directions.

A Advantageous further development of the method according to the invention provides that the at least one first pattern of at least one left and a right partial pattern is built, each one left and a right portion of the one imaged by the imaging member Image part are assigned. In this way, overlays can be left with the right sub-patterns are detected quickly and safely.

Around to be able to judge how big the overlap is the individual image parts, it is intended that at least a left and / or right partial pattern a staircase with steps includes. The overlapping Stair steps then give an indication of the degree of overlap.

In order to be able to close more precisely on the degree of overlapping due to the overlapping steps, it is advantageously further provided that the transverse extent of the steps running from left to right corresponds to the extent of a pixel generated by an exposure head. If one step more is overlapped, the overlapping of the exposure elements in the X-direction by another pixel can be concluded. The width of a pixel is for a Belich but can vary from imaging device to imaging device. It corresponds to the smallest structure width that can be represented by the imaging organs.

It is further provided that the at least one first pattern the Stair steps associated, distinguishable characters, preferably Numbers includes. It will in this way every step on easy Do a certain value of deviation of the actual position of a Bebilderungsorgans from its nominal position assigned. This can be assigned to an overlapping stair step Value of deviation can be detected easily.

It is provided in a further development that at least a right and / or left partial pattern at least one longitudinal, d. H. in the Y direction comprising extending beams. conveniently, can then the steps of the one organ just from the Beams of the adjacent Bebilderungsorgans are covered. Soft steps covered can then provide information about the size of the missposition the associated Give imaging organs.

In a particularly advantageous embodiment, it is provided that a imaging member each a portion of a printing plate imaged, which is wider than the distance between two adjacent imaging organs is.

The Stair steps or the areas of the first patterns that overlap, then a zero point can be assigned. In particular, a Stair step will be marked with the number zero if this Stair step straight or not straight covered by a beam becomes if no X offset hits. On this basis, the adjacent stairs in the transverse direction negative and positive Assigning values that indicate just the pixel count to the in the case of occlusion or not occlusion, the actual position of one of the participants Bebilderungsorgane in the X direction deviates from its nominal position.

It can also be provided that an image file for imaging is used, which has image areas associated with the imaging organs, whose transverse dimensions are each greater than the distances between two Bebilderungsorgane. In this simple way, a desired or defined overlap adjacent image parts can be achieved. The individual imaging organs become, as provided in the image file, the printing plate continues in the image part to illuminate, which already exposed by a subsequent Bebilderungsorgan has been. A gap between the imaged picture parts can thereby advantageously avoided even with corresponding misalignments of the Bebilderungsorgane become.

In order to an offset of the imaging organs in the X-direction in a subsequent exposure considered a printing plate It is envisaged that in each one of the pictorial organ associated image part a first, not hidden by a bar Step is detected. This can preferably be done using optical aids, in particular automatically. If it is provided to identify the stairs according to the invention, the Indicators are read so that it is immediately known how many Pixel is the offset in the X direction. Here are both negative as well as positive amounts possible. The offset here is always the relative offset of the overlay of steps and beams involved imaging organs.

In an alternative embodiment it is also envisaged that in each a Bebilderungsorgan associated image part a last, superimposed by a bar Step is detected. The advantages listed above apply here analogous.

at the determination of an X-offset of a Bebilderungsorgans can X offset of a particular, preferably the first imaging member from a desired position be assumed to be zero. This deviation is arbitrary. The other target positions of the other imaging organs are then each relative target positions to this first imaging organ. The above the described method recognized offsets of an imaging organ are always relative offsets of one imaging organ to the adjacent one Bebilderungsorgan. Depending on the position of the assessed imaging device have to then the deviations of several other successive images management organs be offset to any deviation detected an offset the actual position of a Bebilderungsorgans to its desired position each assign relative to the first Bebilderungsorgan. On this way you can the offsets on a selected, preferably a first imaging organ to be normalized. This applies to both offenses in X as well as in Y direction.

It is advantageously provided that, depending on the position of the detected step or the character assigned to it, the boundaries or the expansions of the image parts assigned to the imaging elements are extended or shortened in the X direction depending on the detected offset of the imaging elements. In this way, any deviations of the actual positions of the imaging organs can be compensated for their desired positions, in particular, the occurrence of a gap between or the overlap of two Bildtei can easily be avoided.

It is advantageously provided that, depending on the position of the detected Step or its associated character the borders or the extent of image areas assigned to the imaging organs, which are covered by an image file intended for imaging, extended depending on the detected offset of the imaging organs in the X direction or shortened and image parts are imaged according to corresponding data of the image file. That way you can the expansions of the image parts are extended or shortened as described.

In an inventive development, it is conveniently provided that the longitudinal distances in the Y direction the at least three spaced second patterns of left / right column each one pixel width different to the Longitudinal distances of right / left column are. In a continuation of a second Pattern of a left / right column into a second pattern of a adjacent right / left column can then be moved to an offset in Y-direction or no offset will be closed, whichever second Patterns just connect to each other so that the second one Pattern in the other continues. Since the distances in each case by the width of a Pixels increase, the measure of the Offset in Y direction in pixels by the position of the matching Pattern to be determined. This determination advantageously takes place based on pixels. For example, if there is no offset from adjacent imaging organs in Y-direction before, so should respectively certain pairs of adjacent second patterns have a defined one Have offset in the Y direction to each other.

The distances the second pattern must be up not necessarily to distinguish the width of a pixel. There are other distances possible, in particular Is it possible, that the distances within a column are different in size. The choice of a distance difference Having a pixel has the advantage of being quick and easy can be detected in the Y direction by a few pixels.

According to the invention is further provided that a second pattern at least three, preferably a plurality of transverse, parallel, longitudinally variable ones having spaced elements. Advantageously, a pairwise Continuation of two second patterns in each other, as described above was thereby easier to assess. The individual elements a second pattern of a right column and a left column a subsequent Image part should be arranged identically. A continuation of two second pattern can be easily recognized, as well as for it all elements of a second pattern in pairs into corresponding elements of a have to continue adjacent second pattern. With the elements can for example, triangles or preferably parallel to, for Y-direction orthogonal lines act.

In a development of the invention is it is advantageously provided that the longitudinal distances of at least three of each spaced apart elements of a second pattern aperiodic, in particular increase or decrease by one pixel width. In pairs Continuation of more than one element of two second patterns is only then possible when the corresponding second patterns adjoin each other without offset. A random one Pairwise continuation of more than one element is advantageously not possible.

In In a particularly advantageous embodiment, the second overlap Patterns of adjoining imaging organs. In this case is at a sufficient overlap the second pattern of adjoining imaging organs too with a very small offset of the patterns against each other on the order of magnitude of 0.01 mm for a first assessment no microscopic examination necessary.

By the overlap is the number of addressed, d. H. the exposed pixels, at a clearer the exposed area, in the area of overlap then lower when the two second patterns are superimposed. If the addressed or exposed areas compared to the non-addressed areas surfaces have a contrast, then the overlap area appears in the in the evaluation sought pair in a different brightness than in couples where the pattern is not without misalignment of one part of the picture continues into the other part of the picture. This change can also be advantageously perceived without a microscope, if the offset itself is of microscopic magnitude.

It is further contemplated that the second patterns of a column are graphically characterized, preferably using numbers, in response to the defined offset of a second pattern of a left / right column of the one image area to a second right / left column pattern of the adjacent image area can. The defined offset in the Y direction results from the image data, which respectively provide different distances of the second patterns of a left or right column. As a result, only a second pattern of a left column to a second pattern of an adjacent right column after the image data has a non-offset terminal in the Y direction. For example, the defined offsets of adjacent second patterns may always increase within the columns.

It Arrangements are also conceivable in which the defined offset within adjacent columns of complementary second patterns is not linear decrease or increase in one direction. Depending on the intervals of the second patterns of a column to each other can be any pairs of second patterns two contiguous columns defined differently Have offenses. It should only matter that so many Different defined offsets are provided that they are all possible Practically by misalignments of Bebilderungsorgane apparent Correspond to offsets. If such an offset then occurs, so be just offset the defined offsets corresponding to this.

conveniently, can be offset by the graphic marking of the Y-direction adjacent second patterns immediately on the offset in Y-direction of the imaging organs getting closed. If numbers are used as identifiers, then can, with appropriate numbering, the two second patterns, which are provided after the image data, without offset in the Y direction to each other to border, to be marked with zero, immediately the pixel-precise Offset can be read. The defined offset in the Y direction of a pair of second patterns is then just of an actually occurring Offset offset, the couple's identification of second patterns with the size of the defined Offset then simplifies the recognition of the actual by misalignments the Bebilderungsorgane occurring offset.

In order to an offset in the Y direction, in particular automatically compensated it is advantageously provided that in each an image part assigned to a signing organ, in each case a second pattern a left or right column is detected, which is substantially without offset to a second pattern of a right or left column of a adjoins the adjacent image area.

The so recognized data can then used according to the invention Be that imaging a printing plate for imaging organs that are each other subsequent Picture parts depict, depending on from the recognized, without successively adjoining second Patterns, in particular under recognition of their graphic markings, in particular Numbers, in further printing processes at later or earlier times starts. The exact changes the deployment times for the imaging organs hang thereby the rotational speed of the drum and the detected offsets the imaging organs in the Y direction.

in the Generally will be for the calculation of the offsets in the X and Y directions of the left image part of the first imaging organ as postulated without offset. This but in principle can be arbitrary to get voted, because only relative offsets need to be corrected. The corresponding offsets the adjoining parts of the picture add up, and the organs of illustration are always set relative to this first imaging device.

An example of a possible method for setting a device for imaging printing plates, from which further inventive features can result, is described below:
A printing plate is imaged in this example in an external drum imagesetter. The printing plate is simultaneously imaged by at least two imaging organs. The Bebilderungsorgane are arranged in the direction of the drum axis, in the X direction, in a row one behind the other. Each imaging member sweeps a narrow band along the Y direction on the drum as it rotates, and by moving the imaging members toward the drum axis, an image portion on the drum surface can be imaged. If the displacement is sufficiently large, a first imaging element passes over the image part already imaged by the preceding adjacent second imaging element, whereby a defined overlapping region can be brought about.

According to the invention, a mark is imaged by the second imaging member at the beginning of the imaging at the boundary to the partial image formed by the first imaging member as a partial pattern of a first pattern according to the invention, for example in the form of a line or a wide stroke extending along the frame boundary in FIG Y-direction extends. At the end of the imaging, a pattern complementary to the mark is imaged by the first imaging member as a second sub-pattern of a first pattern according to the invention, so that it intersects with the mark. According to the present invention, the pattern complementing the mark is designed so that the displacement of the positions of the sub-images in the X direction relative to each other can be quantitatively determined. This can be achieved, for example, in that the pattern complementary to the mark has the shape of a staircase, wherein the width of the steps in the X direction corresponds to the required resolution of the displacement in the X direction, or the smallest feature width that can be represented by the imaging members, if this is required. The height of the steps can advantageously be chosen so that each stage can be assigned a designation that is used in the Evaluation allows a simple identification of the level.

For the assessment then that stage is selected that fits best with the mark, or in another preferred embodiment the complete is covered by the serving as a marker wide line.

The selected Stage then gives information the measure and the orientation of the displacement relative to the desired position relative to the adjacent image part in the X direction.

The Correction of the shift of the image part can then be done on different Done way. A possibility that would be mechanical correction of the positions of the imaging organs in the X-direction according to the determined specifications. As this usually comes with a considerable Effort is generally a purely logical adaptation the areas actually addressed by the various imaging organs and thus the extent or limits of the Image parts adapted.

To This purpose, for example, when going through a shift with positive orientation a gap between the image parts would result the image part, which is imaged by the first imaging element, additional Added pixels. Conversely, the part of the image that is created by the first imaging organ is imaged, pixels subtracted if the shift in the opposite, negative direction is done and there is an overlap of image parts would result.

The for the inventive method required overlap the picture parts can of course can also be achieved in other ways than described above. A possibility that would be the overlap Create at the beginning of the artwork by the beginning of the image part of the second imaging member in the direction of the image part of the first Bebilderung is moved.

As well the method is also applicable if other imaging methods be used, such as flatbed or internal drum imagesetter, where two or more imaging organs are seamlessly connected subsequent image parts to illustrate the limits that may lead to gaps or overlaps.

there The method described can also be in an additional direction to the X direction orthogonal direction are applied when moving in that direction also a through another, adjacent, Bebilderungsorgan to be imaged part of the image to connect seamlessly.

In the example underlying the example of the external drum imagesetter shut down no further parts of the picture appear in a Y-direction of an image part, however, must positioned in the X direction adjacent image parts in the Y direction so be that there is no offset between the image parts.

Around to determine the offset between adjacent image parts becomes According to the invention a second Group of test patterns as second patterns according to the invention at the border imaged between two parts of the picture.

Each Test pattern, by the first Bebilderungsorgan at the border is compared with an additional test pattern, which is the second imaging element is imaged. A test pattern is in each case constructed from a group of elements according to the invention of the second pattern. In the following also the simple term pattern becomes in particular understood as a pattern consisting of the above elements the second invention Pattern is constructed.

One This pair distinguishes the desired state, insofar as that the test pattern from one image part to the other without offset lets continue when both parts of the image are optimally positioned in the Y direction. The rest at least Close two test pattern pairs preferably in both directions along the boundary of the image parts in the Y direction and have a defined between the complementary test patterns Offset, which gradually increases.

are the two parts of the picture are offset from one another in the Y-direction, so does not become the pattern of the nominal state distinguishing pair with the least possible Offset from one part of the picture to the other part of the picture, but the pair of test patterns whose defined offset is the Shift of the image parts in the Y direction best compensated.

advantageously, Each pair can be assigned a name, which is used in the Evaluation allows a simple identification of the couple. to Evaluation is selected that pair whose pattern is with the least possible Offset from one image part to the other image part continues. The Shift leaves then determine from the defined offset of this pair.

As suitable patterns for the method according to the invention, lines which are orthogonal to the Y direction in the X direction are proposed. Particularly advantageous for the evaluation of small displacements of the image parts against each other are a plurality of parallel lines with the least still dissolved by the Bebilderungsorgane structure width. The spacing of the lines is varied aperiodically, thereby facilitating detection of displacement as opposed to equal spacing between the lines. Multiple lines of equal spacing make finding a shift by that very distance problematic. An aperiodically varying distance of the lines is achieved here simply by continuously expanding the distance of the lines within the pattern of a pair. In one embodiment, a one-pixel-wide line is first repeated one pixel apart, then two pixels apart, and so on, increasing the distance to the previous line one pixel at a time, until a convenient pattern dimension for observation is obtained ,

Advantageous for the Assessment of the embodiments described above suitable Pattern, but also in general is an overlap of complementary Pattern or test pattern of a pair.

One first reason for that is that at an unfavorable Shift the image parts in the X direction a gap between the complementary parts of a couple, which is an assessment of the offset, with the pattern of a couple from one part of the picture to the other Image part continues, difficult.

One Another advantage arises for the last described advantageous embodiment of one for the assessment the offset favorable Pattern of one pixel wide lines whose spacing is continuous increases. In this case, with sufficient overlap the supplementary Share even with very small offset of the test pattern against each other in the order of magnitude of 0.01 mm for a first assessment of a couple no microscopic consideration necessary.

By the overlap is the number of pixels addressed, in the case of a light the area exposed, in Area of overlap then lower if the two complementary patterns of a pair are superimposed. If the addressed or exposed areas are not addressed areas have a contrast, then the overlap area appears at the evaluation sought couple in a different brightness than at the couples, in which the pattern is not without offset from one Picture part continues in the other part of the picture. This change can also be perceived advantageously without a microscope, if the offset itself is of microscopic magnitude.

The Correction of the detected displacement in the Y-direction can then done in different ways. One possibility would be the mechanical correction the positions of the imaging organs in the Y-direction according to the determined Requirements. As this usually involves a considerable effort is, is generally a purely logical shift of the image part preferred.

in the Case of the external drum imagesetter on which this example is based can in the Y direction, that is to say the direction of rotation of the drum, by the while each turn recorded traces for the neighboring Bebilderungsorgane at different times. So can the different parts of the picture independent of the mechanical position of the imaging organs in the Y-direction be positioned to each other.

Basically the purely logical adaptation of the positions of the picture parts always possible, if the area that can be covered by the imaging organs is larger as the image part to be imaged.

The The method described can also be orthogonal to the Y direction Direction applied when in the Y direction also, as in the X direction, several image parts to be imaged by different, neighboring, imaging organs to connect to each other without offset.

Advantageous is the combination of both methods, since in general an adaptation the position of the image parts in the X and Y direction is necessary. In a combination the procedure yields the for the determination of the offsets in the Y direction by the method according to the invention advantageous overlap adjoining image parts by themselves, as they are responsible for the implementation of Determination of the position change in the X direction by the method according to the invention is brought about.

Embodiments, which may also give rise to further inventive features to which However, the invention is not limited in scope, are in the drawing shown. Show it:

1 a sketched platesetter with several Bebilderungsorganen and image parts,

2 Partial pattern of a first pattern of three contiguous imaging organs as deposited in an image file,

3 adjoining image parts of an imaged printing plate with partial patterns 2 without X offset,

4 adjoining image parts of an imaged printing plate with partial patterns 2 with X offset,

5 a right and a left column of two adjoining image parts with second patterns,

6 Image parts of an imaged printing plate with first and second patterns.

In 1 is a platesetter 1 outlined. A printing plate 2 is by means not shown fastening members on a drum 3 clamped.

To illustrate the printing plate 2 Here are eight imaging organs 4 shown. But it is also quite possible that an illustration of the printing plate 2 with more than eight imaging organs 4 or only with two imaging organs 4 can be done. The imaging organs 4 should here be exposure heads with laser diode arrays. In principle, however, are also different Bebilderungsorgane 4 usable, the pressure plate 2 digital, in particular image by pixel.

The imaging organs 4 are here on a spindle 5 attached. Via data lines 19 become the imaging organs 4 supplied with data of an image file. The image data are subdivided into image regions, each of which is a Bebilderungsorgan 4 assigned. An illustration organ 4 is then addressed so that there is a corresponding image part 6 on the printing plate 2 imaged. The drum 3 becomes an illustration in the direction of the arrow 7 shot while the imaging organs 4 on or with the spindle 5 in the direction of the double arrow 8th perpendicular to the direction of rotation of the drum 3 to be moved. The width 27 a picture part 6 This corresponds essentially to the distance 15 two neighboring imaging organs 4 ,

Through these two orthogonal movements, the rotation of the drum 3 on the one hand and the lateral displacement of the imaging organs 4 On the other hand, describe the Bebilderungsorgane 4 an orthogonal coordinate system 9 on the printing plate 2 , The X direction of this coordinate system 9 points in the direction of movement of the Bebilderungsorgane 4 while the Y direction is due to the rotation of the drum 3 is determined and opposite to the direction of rotation.

This is done by the different imaging organs 4 a complete printed image on the printing plate 2 exposed. The individual parts of the picture 6 the imaging organs 4 encounter at connection points 10 on the printing plate 2 together. By tolerances, installation inaccuracies of Bebilderungsorgane 4 or similar, the image parts at the connection points 10 initially have Ver satze. It can occur both offsets in the X direction and in the Y direction.

The 2 shows several partial patterns 11a . 11b a first pattern 11 five contiguous imaging organs 4 after an image file. The same elements are provided with the same reference numbers as in 1 , By means of these first patterns 11 X-offsets can be detected.

A first pattern 11 is from two sub-patterns 11a and 11b constructed, each with sub-patterns 11b and 11a from adjacent imaging organs 4 cooperate. The two partial patterns 11a and 11b two adjacent imaging organs cooperate in so far as that from their interaction, an offset of two adjoining Bebilderungsorgane 4 can be detected, as will be shown below. The first patterns 11 are, as they are shown here z. B. saved as a bitmap in a file.

From the first patterns 11 a first, left illustration organ 4 is only the right partial pattern 11a and from a last, right-imaging organ 4 only the left partial pattern 11b shown.

The right partial pattern 11a a first pattern 11 is in the case illustrated a staircase with stairs 20 , The stairs 20 have a longitudinal extent in the Y direction, which exceeds the transverse extent in the X direction. The width of the stairs 20 in the X direction results from the least of the Bebilderungsorganen 4 illuminable structure width, in this case about 10 microns. Next to the stairs 20 , which adjoin each other in the X direction without gap, there are identifiers for identification, in this case digits 21 ,

The left partial patterns 11b are wide stripes, or bars whose left edge is exactly at the beginning of the image area 16 a picture area 13 lie. This beginning 16 a picture area 13 is indicated by a solid line. The finishing picture 17 a picture area 13 on which the outer right steps 20 the partial pattern 11b ends is also indicated by a solid line. Every picture area 13 is doing a Bebilderungsorgan 4 assigned and in the case shown here in each case comprises at least a first pattern 11 , The transverse extent 14 a picture area 13 is determined by the distance of the beginning of the artwork 16 and the end of the artwork 17 established. The lines to mark the beginning 16 and the end 17 are shown here only for clarity and are not on a printing plate 2 imaged or are part of a file. The ends 17 and the beginnings 16 adjacent image areas 13 shoot directly at each other here.

The transverse extent 14 in the case shown here is 192 mm. But there are also other values, in particular different values for different image areas 13 possible. The distance 15 two imaging organs 4 is in the case shown here 190 mm, here it is symbolic for better comparison with the transverse extent 14 as the distance between two lines 18 located.

When exposing a printing plate 2 according to the data of the image areas 13 as depicted here become the organs of illustration 14 according to the transverse dimension 14 moved while the drum 3 rotates. Each illustration organ 4 thereby exposes the image area assigned to it 13 on the printing plate 2 , Because the transverse extent 14 an image area 13 is greater than the distance 15 the participating imaging organs 4 close the artwork end 17 of an illustration organ 4 and the beginning of the artwork 16 of the following imaging member 4 no longer on each other, it comes to an overlap of the of the Bebilderungsorganen 4 on the printing plate 2 illuminated first brands 11 , in particular of the partial brands 11a and 11b two first brands 11 , This overlap is particular in 3 shown.

For easier identification are the steps 20 distinguishable signs, here numbers 21 assigned. The values of the numbers 21 here lies between -5 and +4. This is a simplified and limited representation of factual circumstances. Due to the overlaps of the stairs 20 with the left partial patterns 11b an adjoining imaging device 4 should be on an offset in the X direction of the two imaging organs 4 be closed to each other. The width of the right partial pattern 11a ie the number of steps 20 should therefore be chosen so that even the largest expected shift of a Bebilderungsorgans from its desired position can still be determined. In a realistic case, for example, it can be assumed that the deviation can not be more than 2 mm in both directions. The width of a step 20 should the least possible, through the Bebilderungsorgane 4 representable structure width, here correspond to 10 microns. Thus, to cover the entire width of 4 mm, resulting from the maximum deviations, a total of 401 steps 20 needed, then with numbers accordingly 21 from -200 to +200.

In 3 is a printed image as shown by the in 2 illustrated first pattern 11 is generated when the Bebilderungsorgane 4 have no offset in the X direction.

How to 2 was executed, the transverse dimensions deviate 14 the image areas 13 from the distances 15 the imaging organs 4 every 2 mm. The picture parts 6 therefore intersect between the lines of the Bebilderungsende 17 and the beginning of the artwork 16 , Whereby a left illustration organ 4 each in the picture part 6 pictured in it, the one next to an imaging organ 4 assigned. For a better overview here is the line that the Bebilderungsende 17 features dotted and the beginning of the artwork 16 associated line dashed. An overlap of adjacent image parts 6 is through the right of the beginning of the artwork 16 lying line of Bebilderungsende 17 of the previous imaging device 4 easy to understand. Again, the number of steps is 20 purely symbolic, as well as the distance from Bebilderungsanfang 16 and finishing 17 neighboring imaging organs 4 , In a realistic case, the steps would become 20 and the left part marks 11b overlap by about 2 mm, always under the condition that there is no offset in the X direction. The stairs 20 are arranged so that just the step 20 that with the number 21 "0" is marked completely off the bar of the left partial pattern 11b of the adjacent part of the picture 6 is covered.

Should there be an offset in the X-direction, the bars of the left partial pattern become 11b the stairs of the right partial pattern 11a Depending on the size of the offset overlap differently, then there will be different levels of stairs 20 obscured by the beams. Based on the last fully concealed step 20 may be the relative displacement of the adjacent imaging organs 4 be recognized. Here is in particular to the last step 20 assigned number 21 usable as an indication of the relative offset. Here is the width of a step 20 about 10 μm, multiply the number 21 the last hidden step 20 with 10 microns, we obtain directly the relative displacement of the imaging organs 4 in μm. The number 21 by itself indicates the offset in pixels.

A corresponding representation of a printed image with patterns 11 in which a displacement of the imaging organs 4 occurs in the X direction is in 4 shown. Like reference numerals designate like elements again.

The distances between the end of the artwork 17 and the beginning of the artwork 16 two neighboring imaging organs 4 varies, depending on the X offset.

There are here, at least in part, five Bildtei le 6 shown, the five consecutive imaging organs 4 be assigned. Here it should be assumed that a first image part 6 ⁱ from the outermost imaging organ 4 was imaged. Here is in particular only the right partial pattern 11a shown. The following three imaging organs 4 illustrated the picture parts 6 ⁱⁱ . ^Iii and 6 ^iv , The last picture part shown 6 ^v became with the fifth illustration organ 4 imaged, of which only the left partial pattern 11b is shown.

The first imaging organ 4 is assumed to be without substitution. The bar of the left partial pattern 11b of the second imaging member 4 hides the stairs of the right partial pattern 11a of the first imaging organ 4 so that still the number 21 "-2" is recognizable while the associated step 20 is completely obscured. It can be concluded that the second Bebilderungsorgan 4 a relative offset in the X direction to the first imaging member 4 of -2 pixels

In the same way, the relative displacements of the other Bebilderungsorgane 4 be determined. By addition of the present relative displacements, the respective displacements of an arbitrary imaging element can then be determined 4 in relation to the first imaging organ 4 be determined.

To correct the so-called offsets in the X direction, the laser diodes of a Bebilderungsorgans 4 that cause the offset to be turned off first. It can be provided that an imaging device 4 the entire picture part 6 then imaged without these diodes. It is also possible that these diodes only for the period in which they still have the image part 6 of the previous imaging device 4 would be turned off.

Based on each pair of co-operating partial patterns 11a . 11b contiguous imaging organs 4 can the deviation of the distance 15 two neighboring imaging organs 4 read from the nominal distance. From the stairs of the partial pattern 11b in the image area 6 ⁱ of the leftmost imaging organ 4 are the stairs 20 with the numbers 21 Recognize "-5" to "-3". The stair step 20 with the pay 21 "-2" is completely off the bar of the partial pattern 11b of the adjacent image part 6 ⁱⁱ covered. As part of the resolution of the process can thus be determined that the image area 6 ⁱⁱ belonging to Bebilderungsorgan 4 relative to the left most imaging device is shifted by two pixel widths from their desired position to the left. Similarly, the shift from the desired position relative to the adjacent Bebilderungsorganen 4 be determined for all other imaging organs. With respect to the left neighbor, in the case of the present example, a shift of +4 pixel widths is determined for the ^Iii , -2 pixel widths for the too 6 ^iv and +3 pixel widths for the 6 ^v belonging to Bebilderungsorgane. The criterion used here for the selected stair step 21 is that she needs to be completely covered. The criterion depends on the exact imaging process. In the present case, it takes into account the experience that in the invention underlying exposure of printing plates 2 a gap between the image parts 6 easier to recognize than an overlap. In the case of other imaging methods, other criteria may be more appropriate.

If a positive offset occurs in the X direction, then it can be provided that the imaging device 4 which is a picture part 6 left of the image part 6 imaged with the positive offset, so far in the area of the adjacent Bebilderungsorgans 4 illustrated that gaps are avoided. In particular, it can be provided for this purpose that the corresponding image parts 6 , for example 6 ⁱⁱ and ^Iii be increased or decreased. These changes are made within a file containing the data of an artwork to be made. For example, these changes can be calculated by a CPU just before a print job is submitted to a press.

5 shows a right column 12a and a left column 12b each with four second patterns 22 , The two columns 12a and 12b can also overlap what z. B. may be the case if an offset of the two, the columns 12a . 12b pictorial illustration organs 4 in the X direction. In particular, an overlap can also be provided in the absence of offset. In the case presented here, the presentation of an overlap of the overview was omitted. Furthermore, each column 12a . 12b even more, not shown here second pattern 22 exhibit.

Every second pattern 22 has elements 23 on. These elements 23 are here parallel lines orthogonal to the Y-direction, which are aperiodically spaced in the Y-direction so that the distance of the elements 23 a second pattern 22 is continuously increased. The enlargement of the distance here corresponds in each case to the width of a pixel. It is first repeated a one-pixel-wide line at a distance of one pixel, the next line is then repeated at a distance of two pixels and the distance of further lines then further increases by one pixel.

The distances 24 the second pattern 22 the right column 12a in the Y direction are equidistant. The same applies to the distances 25 the second pattern 22 the left column 12b , The distances 25 are here one pixel larger than the distances 24 , Other ratios of the distances 24 and 25 are also possible, they just should not be the same size.

The width of the elements 23 in the Y-direction, the least corresponds to the imaging organs 4 resolvable width, ie the width of a pixel.

In the case shown here, they show the image parts 6 ⁱ and 6 ⁱⁱ pictorial illustration organs 4 no offset in the Y direction, the patterns shown here 22 can also exist as a bitmap in a file. The image files of both parts of the picture 6 ⁱ and 6 ⁱⁱ are designed so that the elements 23 the second pattern 22 the right and left column 12a . 12b that with a number 26 "0" marked are abutting each other without offset. The lines shown here are then from the first part of the picture 6 ⁱ in the second part of the picture 6 ⁱⁱ continued without offset. All other lines of the pattern 22 the two columns 12a . 12b show the transition from an image part 6 ⁱ in the other part of the picture 6 ⁱⁱ a corresponding offset.

The second patterns 22 are each graphical identifiers in the form of numbers 26 assigned. These numbers 26 denote the expected offset of two adjacent second patterns 22 if the appropriate imaging organs 4 just have no offset in the Y direction. The payment 26 assume corresponding positive and negative values which respectively correspond to the pixel number of the expected offset. The Elements 23 adjacent pattern 22 have up to at most one line in each case an offset in the transition from the image part 6 ⁱ in the picture part 6 ⁱⁱ on, if you look at the patterns 22 with the number 26 "0" is missing.

Assign the illustration organs 4 relative to each other on an offset in the Y direction, so are the columns 12a and 12b shifted against each other. This will cause the offsets of adjacent patterns 22 changed, leaving other second patterns 22 elements 23 have, the elements without offset 23 an adjacent pattern 22 connect. Because the adjacent patterns 22 may just have a designated offset by a certain number of pixels, depending on the number 26 the pattern 22 , which now have no offset, are recognized by which pixel number the columns 12a and 12b were shifted against each other. Is the second pattern 22 z. For example, the number 26 Assigned "-7", so is the right Bebilderungsorgan 4 by seven pixels relative to the neighboring left imaging device 4 still below, ie opposite to the Y-direction of the coordinate system 9 postponed. This directional assignment applies only when the drum 3 rotated counter to the Y direction. Turns the drum 3 in the Y-direction, contrary statements apply. If the Y offset does not have integer pixel numbers, then an offset of half a pixel and below may be interpreted as being offset.

The thus detected offset in the Y direction can then be corrected, for example, by the right-hand imaging element 4 starting with the exposure to an underlying image file by the time necessary for the imaging of the seven pixels. This also applies only to rotation of the drum 3 against the Y-direction.

The over the numbers 26 Recognized Y-offsets are always relative offsets of the involved imaging organs 4 , However, these offsets can be added up and onto a first imaging organ 4 be obtained.

In 6 is a section of one with first patterns 11 and second patterns 22 illustrated printing plate 2 shown. They are picture parts 6a ⁱ . 6a ⁱⁱ . 6a ⁱⁱⁱ and 6a ^iv shown, different from the picture parts 6 which have been shown in the other drawings, can be different or can be identical with them, they are here in their entirety also simply as parts of the picture 6 designated.

From the printed image shown X and Y offset and thus the deviations of the actual positions of the desired positions of the imaging organs 4 recognized and in the imaging of other printing plates 2 be taken into account.

In the upper part of the picture parts 6 are the first patterns 11 for determining the X offset. The finishing picture 17 and the beginning of the artwork 16 are each indicated by dashed lines, which are shown for illustrative purposes only. The area between the end of the artwork 17 an imaging device 4 and the beginning of the artwork 16 a right adjoining Bebilderungsorgans 4 designates the connection point 10 of the two imaging organs 4 , In a case without offset, artwork will end 17 and artwork beginning 16 lie in the same position. For a test exposure, as described here, but should the image parts 6 the imaging organs 4 just overlap, leaving it always at a distance of the imaging end 17 from the beginning of the artwork 16 comes. In a real case, as he should be sketched here, the image parts 6 overlap due to inaccuracies other than intended, the distances of the imaging end 17 from the beginning of the artwork 16 vary accordingly from junction 10 to junction 10 depending on the involved imaging organs 4 ,

In the lower part of the image parts 6 are the second patterns 22 to detect the offsets in the Y direction shown. Due to the intended overlaps of the image parts 6 and the additional X offset, the second patterns overlap 22 in an advantageous manner so that Y-offset of the elements 23 at the transition from a picture part 6 in an adjacent part of the picture 6 alone be well recognized due to the differences in brightness. An analysis of the brightness values can be carried out, for example, optically via sensors or via a user.

The methods how offsets can be determined and how real first and second patterns 11 and 22 are constructed, have already been explained in the previous figure descriptions. It then arise for the picture parts shown here 6 following offenses:
6 ⁱⁱ is opposite 6 ⁱ shifted by 3 pixels to the left and has no offset in the Y direction,
^Iii is opposite 6 ⁱⁱ 2 pixels to the right and one pixel to the top,
6 ^iv is opposite ^Iii 2 pixels to the left and 2 pixels to the bottom.

These offsets can then be compensated for further print jobs, which should be imaged according to these test patterns. The X offset can thereby mechanically or via different controls of the optical elements of the Bebilderungsorgane 4 be compensated, while the Y-offset, for example, on different temporal activations of Bebungsungsorgane 4 can be compensated.

A mechanical correction of the positions of the Bebilderungsorgane in the X direction according to the determined specifications is usually associated with a considerable effort, it is therefore a purely logical adaptation of the different Bebilderungsorganen 4 actually addressed areas and thus the extent or boundaries of the image parts 6 customized.

For this purpose, for example, if a gap between the image parts resulted from a shift with positive orientation, the image part would become 6 by the first organ of the illustration 4 is imaged, additional pixels added. Conversely, the image part 6 by the first organ of the illustration 4 is imaged, pixels are subtracted when the shift is done in the opposite, negative direction and there is an overlap of the image parts 6 would result.

Corresponding methods described here can also be transferred if several imaging organs 4 in Y-direction are switched one behind the other and this matrix of Bebilderungsorganen should be adjusted without offset.

Claims (6)

Method for adjusting a device for imaging printing plates ( 2 ) having at least two imaging members spaced apart in an X-direction (US Pat. 4 ), which are provided image parts ( 6 ) of a printed image can be imaged seamlessly and without offset to each other, including the Bebilderungsorganen ( 4 ) Target positions are assigned and actual positions of the imaging organs ( 4 ) are checked at least relative to each other at least in a Y-direction orthogonal to the X-direction and undesirable effects are prevented or compensated by detected misalignments, wherein for checking the actual positions in the Y-direction of each imaging device ( 4 ) the pressure plate ( 2 ), each having a right and a left column extending in the Y direction ( 12a . 12b ) each having at least three second patterns spaced apart in the Y direction ( 22 ) so imaged that in each case the right column ( 12a ) of an image part ( 6 ) of an imaging device ( 4 ) to the left column ( 12b ) of an adjacent image part ( 6 ) or overlaps with it, this second pattern ( 22 ) at least three aligned in the X direction, parallel, in the Y direction around mutually different longitudinal distances ( 24 . 25 ) spaced elements ( 23 ) having. Method according to claim 1, characterized in that the longitudinal distances ( 25 ) of the at least three spaced-apart second patterns ( 22 ) of the left column ( 12b ) each by one pixel width different from the longitudinal distances ( 24 ) of the right column ( 12a ) are. Method according to claim 1 or 2, characterized in that the longitudinal distances ( 24 . 25 ) of the at least three spaced-apart elements ( 23 ) at least one of the second patterns ( 22 ) increase or decrease evenly aperiodically. Method according to at least one of claims 1 to 3, characterized in that the second patterns ( 22 ) of a column ( 12a . 12b ) graphically, depending on the pattern ( 22 ) detectable offset of a left / right column ( 12a / 12b ) of the one image part ( 6 ) to the right / left column ( 12b / 12a ) of the adjacent image part ( 6 ). Method according to claim 4, characterized in that in each one of the imaging organs ( 4 ) assigned image part ( 6 ) a second pattern ( 22 ) a left ( 12a ) or right column ( 12b ), which is essentially offset from one another second pattern ( 22 ) a right ( 12b ) or left column ( 12a ) of an adjacent image part ( 6 ). Method according to one of claims 4 or 5, characterized in that the time at which in subsequent printing processes or images of a printing plate ( 2 ) the illustration for imaging organs ( 4 ), the adjoining image parts ( 6 ), depending on the detected, seamlessly adjoining second patterns ( 22 ) is set under recognition of their graphic markings.